Pressure and temperature regulator for aircraft bleed air system



United States Patent [72] Inventors George C.Rlnnenberg [50] Field ofSearch 165/31,:52, Canton; 1 l5,40;98/l.5; 236/92 Bartholomew J.Davison, Simsbury, and Charles B. Brahm, Ellington, Connecticut [5References Cited [21] AppLNo. 752,046 UNITED STATES PATENTS 1 1 FiledAug-11,1968 2,474,441 6/1949 Sparrow 165/15 [45] Patented Nov. 3, 19702,858,075 10/1958 Le May, Jr. et al. 165/15 1 Asslsnee United Alma"Cwwafion 3,445,317 5/1969 Marshall et al. 165/40 East Hartford,Connecticut fipontionof Dehware Primary Examiner-Charles SukaloAttorney-Norman F riedland [54] gfig ggi gggg i ABSTRACT: The load on aprecooler heat exchanger is con- 6 i In in H trolled by utilizing anexisting pressureregulating valve and 8 a locating thepressure-regulating valve in proximity to the heat [52] U.S.Cl. 165/32,exchanger and limiting the flow through the precooler as a 98/ 1.5,236/92 function of temperature sensed downstream of the heat. [51]lnt.Cl. ..GOSd 23/00 exchanger.

. 1 r-ENGINE BLEED i Q. ff 5% AIR AMBIENT l 5/. RAM HEAT 54 g/ A|REXCHANGER 55 a I 7/; I 72 42 1 I 52 1' Z! ,8 M 1 I 4 M 2 s i l 1 t 1 l'52 z I i 3 /VALVE r i 90 c1055 20 l v f .56 AMBIENT 1----D o. n l 1 L4MANIFOLD Patented Nov. 3, 1970 N O s 5 R V i! w .i mm W? WWW Ema? w O uH H CB n X A So T fiow mfi PEEE W 12 r L In. Q 55m @265 m E B N E N N AW R 2/ E c R O E G M v 8 E 22 mo 2E ATTORNEY PRESSURE AND TEMPERATUREREGULATOR FOR AIRCRAFT BLEED AIR SYSTEM CROSS REFERENCE TO RELATEDAPPLICATIONS This application relatesto an application entitled CombinedPressure and Temperature Regulator, filed by Bartholomew J. Davison onthe same date and assigned to the same assignee.

BACKGROUND OF THE lNVENTlON in the air-conditioning systems for aircraftit is customary to bleed off air from the engine which is cooled forair-conditioning purposes. The same air can also be utilized to driveaccessories which usually have varying load requirements.

in designing the heat exchanger for cooling the engine bleed air, onehas to take into consideration the load capacity for the severestcondition, that is, when the maximum bleed air is required at all engineoperations.

In certain applications, however, the heat exchanger would be so largeto handle the heat load for the extreme conditions, which may occur onlyoccasionally, that its size and weight would not be acceptable foraircraft applications.

We have found that we can reduce the size of the heat exchanger whilereducing the possibility of overheating the air to an intolerable level,by locating the pressure regulator in proximity to the heat exchangerand limiting flow as a function of temperature sensed downstream of theheat exchanger.

SUMMARY OF THE INVENTION A primary object of this invention is toprovide means to limit the heat load capacity of a heat exchanger in anaircraft air-conditioning system.

Another object of this invention is to provide means to limit the heatload capacity of a heat exchanger in an aircraft airconditioning systemby limiting flow through the heat exchanger as a function of temperatureof the fluid sensed downstream thereof.

Other features and advantages will be apparent from the specificationand claims and from the accompanying drawings which illustrates anembodiment of the invention.

The sole figure schematically illustrates a preferred embodiment of thisinvention wherein the temperature sensor is generally indicated bynumeral and the combined pressure and temperature controller isgenerally illustrated by numeral l2v in the preferred embodiment duct 14serves to transmit pressurized fluid bled off a turbine type ofpowerplant which fluid is precooled by a heat exchanger prior to beingdistributed to an air-conditioning system for cooling the cabin of theaircraft and/or other pneumatic drives.

Throttle valve 16 which may take the form of a suitable butterfly valveis disposed in duct 14 downstream of the heat exchanger and serves toregulate the pressure and temperature downstream thereof in accordancewith the signal produced by controller 12 as will be describedherewithin. Movement of valve 16 is controlled by actuator 18 whichcomprises diaphragm 20 dividing chamber 22 into two subchambers 24 and26. Diaphragm 20 carries plunger 28 which in turn is suitably connectedto shaft 30 by linkage 32. The linkage serves to rotate the shaft 30which in turn is connected to the valve element of valve 16 forimparting rotary movement thereto. A second diaphragm 34 closes off theend of chamber 24 and is continually subjected to high pressure.

Looking for the moment at the pressure controller 12 which serves tocontrol the pressure in duct 14 by varying the area of valve 16,pressure sensed downstream of valve 16 is admitted into chamber 40 vialine 42 where it acts on the face of diaphragm 44. Force developed bydiaphragm 44 is transmitted to platen 46 via spring 48 which in turntransmits a force to fulcrum lever 50 via the depending member 52.Fulcrum lever 50 pivots about the pivot 54 to control flapper valve 56connected on the opposite end thereof. Flapper valve 56 moves relativeto the orifice 58 located at the end of line 60 which serves to controlthe flow of fluid discharging therefrom for controlling the pressuredrop across restriction 62. Obviously, this controls the pressure inlines 60 and 64 and the pressure in chamber- 26.

From the foregoing it is apparent that flapper element 56 contro sactuator 18 and hence valve 16 as a function of pressure in the duct 14.Obviously, when flapper element 56 abuts against orifice 58 no pressuredrop will be evidenced across restric ion 62 and the pressure in chamber26 and hence pressure acting on face of diaphragm 20 will be the same asthe pressure in chamber 68 acting on the face of diaphragm 34. Sincediaphragm 20 is larger than diaphragm 34 the forces created thereby willcause the actuator to move leftwardly rotating valve 16 in the full openposition.

Conversely, when the flapper element 56 is caused to move away fromorifice 58 a pressure drop will be evidenced across fixed restriction 62reducing pressure in chamber 26 allowing the actuator to moverightwardly to rotate valve element 16 toward the closed position.

An adjustable screw 63 is disposed in chamber 40 to abut againstdiaphragm 44 to limit the travel thereof. This screw is so positionedthat when under normal pressure control, without excessive temperatures,the downstream pressure is free to fully open valve 16. This screwprovides one of the elements of temperature override as described laterso as to achieve temperature-limiting accuracy.

Position feedback is effectuated by varying the height of spring 74which abuts against fulcrum lever 50 and slideable spring retainer 72.As can be seen by the drawing, cam 70 suitably mounted for rotation isrotated by shaft 30. Hence, the position of valve 16 is transmitted viashaft 30, cam 70, spring retainer 72 and spring 74 to fulcrum lever 50for restoring the flapper valve element to its original position tobalance out the system.

The next portion of the description will describe the temperature sensorand controller. The temperature sensor and controller 10 transmits'apressure signal to the pressure and temperature controller 12 which isproportional to temperature in the duct 14. Temperature ofthe fluid inthe duct line is sensed by the temperature sensor comprised of elementsand 82 which are composed of materials with different coefficients ofthermal expansion. As temperature increases 80 expands more than 82resulting in a counterclockwise motion of hellcrank 84 pivotallyconnected to pivot 86. Hence, a change in temperature rotates bellcrank84 which has one end bearing against spring 88. This end carriesadjustable spring retainer which serves to position spring 92 againstfulcrum lever 94. This spring is balanced by adjustable spring 96 andserves to impart a balancing force on fulcrum lever 94 which pivotsabout pivot member 98. This in turn positions flapper element 100relative to orifice 102 located at the end of pipe 104. Ohviouslyfulcrum lever receives a force imparted by the temperature sensor at oneend of the pivot and an additional force imparted by the fluid impingingon flapper element 100, discharging from pipe 104. The purpose of thisarrangement is to eliminate the varying pressures that are normallyattendent a servosystem that utilizes engine bleed as supply pressure,thus pressure in pipe 104 is proportional only to temperature in duct14.

From the foregoing it is apparent that fulcrumed lever 94 sees theforces imparted by the fluid discharging from orifice 102 and the forceof spring 92 less the spring force of spring 96. This arrangement makesfulcrum lever 94 insensitive to varying supply pressure.

Stop 93 serves to prevent the temperature controller from producing asignal when the temperature sensed by temperature sensor 80 is below apredetermined value. Hence, it is obvious that in this mode, that iswhen spring retainer 90 abuts against stop 93 the temperature controlleris rendered inoperative and the pressure in line 104 is held to aconstant value resulting in operation with only the pressure regulatorcontrolling, via diaphragm 44. Conversely, when diaphragm 44 abutsagainst screw 63 the pressure regulator is rendered inoperative and thetemperature controller can be the sole controller.

The temperature controller servo works in a manner similar to thepressure regulator servo. Fulcrumed lever 94 carries at one end flapper100 which moves relative to orifice 102 for varying the pressure dropacross fixed restriction 106. This acting on the face of diaphragm 46.The force generated by diaphragm 46 is transmitted to fulcrumed lever 50for controlling flapper 56 and hence actuator 18 for moving throttlevalve 16. Hence, when temperature exceeds a predetermined value,notwithstanding the pressure, valve 16 is moved to a closed position toreduce the flow in the heat exchanger and prevent the temperature fromexceeding a predetermined value.

While this specification shows a preferred embodiment where the pressureregulating valve is mounted downstream of the heat exchanger, it is tobe understood that this mechanism can be located upstream of the heatexchanger. However, it is necessary that the temperature sensor islocated downstream of the heat exchanger.

It should be understood that the invention is not limited to theparticular embodiments shown and described herein, but that variouschanges and modifications may be made without departing from the spiritor scope of this novel concept as defined by the following claims.

We claim:

1. For an aircraft pneumatic system utilizing propulsive engine bleedair having a precooler for precooling the air bled from the engine priorto the use thereof comprising, in combination:

a duct interconnecting the engine and the heat exchanger for passingengine bleed air therethrough;

valve means in said duct located downstream of said heat exchanger forcontrolling pressure and flow;

means responsive to pressure in said duct for controlling said valvemeans for limiting the pressure of the engine bleed air; and

means responsive to the temperature in said duct downstream of the heatexchanger for limiting the temperature of the engine bleed airdischarging from said heat exchanger.

2. An aircraft pneumatic systemas described in claim 1 wherein said heatexchange places said engine bleed air in indirect heat exchange relationwith ram air.

3. For an aircraft pneumatic system utilizing propulsive engine bleedair having a precooler for precooling the air bled from the engine priorto the use thereof comprising, in combination:

a duct interconnecting the engine and the heat exchanger for passingengine bleed air therethrough;

valve means in said duct for controlling pressure and flow;

means responsive to pressure in said duct for controlling said valvemeans for limiting the pressure of the engine bleed air;

means responsive to the temperature in said duct downstream of the heatexchanger for limiting the temperature of the engine bleed airdischarging from said heat exchanger; and

a pressure sensor sensing the pressure downstream of said heatexchanger.

4. An aircraft engine bleed air system utilizing bleed air forair-conditioning and pneumatic drives comprising, in combination:

duct means connecting the air-conditioning system and pneumatic drives;

a heat exchanger disposed in said duct upstream of the airconditioningsystem and pneumatic drives;

means including at least one valve disposed in said duct for controllingthe flow through said heat exchanger;

said means being responsive to pressure of the engine bleed airdownstream of said valve in said duct; and

said means also being responsive to temperature of the engine bleed airdownstream of said heat exchanger.

5. For an aircraft pneumatic system utilizing propulsive engine bleedair, comprising, in combination:

a duct interconnecting the engine and the aircraft pneumatic system forpassing said engine bleed air therethrough;

a heat exchanger in the duct for cooling the air bled from the engine;

valve means in said duct;

means responsive to pressure in said duct downstream of said valve forcontrolling said valve means for limiting the pressure of the enginebleed air;.and

means responsive to temperature in said duct downstream of said heatexchanger for controlling said valve means for limiting the temperatureof the engine bleed air discharging from said heat exchanger.

6. An aircraft engine'bleed air system utilizing bleed air forair-conditioning and pneumatic drives comprising, in combination:

duct means connecting the air-conditioning system and pneumatic drives;

a heat exchanger disposed in said duct upstream of the airconditioningsystem and pneumatic drives;

means including at least one valve disposed in said duct for controllingthe flow through said heat exchanger;

said means being responsive to pressure of the engine bleed air in saidduct; and

said means also being responsive to temperature of the engine bleed airintermediate said valve and said heat exchanger downstream of said heatexchanger.

